Do AlphaZero/MuZero learn faster in terms of number of games played than humans?
According to Table S3 of the AlphaZero paper (p. 15)

AlphaZero was trained for 9 hours and, during these 9 hours, it played 44 million games of chess.
According to this Wikipedia article, the longest human lifespan is that of Jeanne Calment, who lived to age 122 years and 164 days.
Let's assume that humans cannot live more than 123 years (which is a reasonable assumption, although this record could eventually be broken). Let's also assume that a chess game lasts at least 10 minutes, which means that you can play at most 6 games in 1 hour, which means that you can play at most $6*24 = 144$ games in one day (assuming that you never sleep, which is, of course, impractical, but I'm just trying to show you an upper bound). Let's say that a year has 365 days. So, here is roughly the maximum number of games that a human could play
$$
6*24*365*123 = 6464880 \tag{1}\label{1},
$$
which is smaller than 44 million games by a factor of more than 6, i.e. any human could at most play 1/6 of the games that AlphaZero played, and \ref{1} is a very loose upper bound that doesn't take into account that humans need to sleep, eat, and do many other things.
So, humans learn to play chess a lot slower than AlphaZero. This is not surprising at all, given that computers can perform calculations a lot faster than us (that's why they are called computers), and this has been the case for many years. We (humans) just made computers make the right calculations for them to approximately play chess better than us. That's it.